1. Field of the Invention
The present invention relates to a liquid crystal panel manufacturing process, and in particular to a pattern matching method, apparatus and a line width measuring machine.
2. The Related Arts
In the manufacturing process of the liquid crystal display, to determine if the coating is successful, it needs to measure the coating line width of the coated glass substrate. At the first, it needs a step of the pattern matching for the measured sample and the designed pattern to position the sample.
Generally, in order to form multiple patterns on the transparent glass substrate by coating process in the measured sample, it contains many segments in the patterns. The line width measuring machine needs to measure the width of the line segment. In order to match the patterns, at least one standard pattern used for matching is further coated at the predetermined position on the measured sample, and the patterns at different position of the standard pattern may be different. Accordingly, a designed pattern of the standard pattern is stored in the line width measuring machine (or computer), and the said pattern matching refers to comparing the standard pattern on the measured sample with a corresponding designed pattern which has been stored in advance. If the comparing result for both is the same or reaches a certain degree of similarity, the match is successful. After the successful matching, the pattern on the measured sample can be moved to the middle position to measure the line width.
However, in the prior art, once the manufacturing process of the liquid crystal panel occurs instability, it usually shows a certain degree of gray-scale on the measured sample, as shown in FIG. 1, wherein A represents the standard pattern on the measured sample, B represents the corresponding design pattern which is stored in advance, wherein the standard pattern A exists in a certain gray-scale, which differs from the designed pattern B in gray-scale. In this situation, it often leads to failed pattern matching. Actually, the differences of the gray-scale in the manufacturing process of the liquid crystal panel are acceptable. Therefore, this situation will easily lead to that the line width cannot be measured and delay the schedule.